Sound absorbing panel and system

ABSTRACT

Disclosed are a sound absorbing panels and a sound absorbing system using such panels, particularly for use in reducing highway and railway noise. The panel includes an enclosure including a first panel face with a number of apertures or holes to allow sound passage, where the ratio of the area of the apertures to the total area of the first panel face is set at a predetermined percentage. The enclosure is configured such that an inner surface of the first panel face is proximate to a fibrous sound absorbing material with an area approximately equal to the total area of the first panel face. The panel enclosure may have various shapes and configurations for optimal sound absorption, and may be configured in a sound absorbing system such that one or more of the panels are mountable to existing structures, such as sound barrier walls in a retrofit manner.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

The present Application for Patent claims priority to ProvisionalApplication No. 61/458,485 entitled “Sound Absorbing Barrier forHighways and Railroads” filed Nov. 24, 2010, and hereby expresslyincorporated by reference herein.

BACKGROUND Field

The present disclosure relates generally to sound absorbing panels, andmore specifically to a sound absorbing panel for use in applicationssuch as reducing vehicle noise from roads and railways.

Background

It is known that roadways and railways, for example, are sources ofsignificant noise approximately 85 decibels and upward. In order tomitigate this noise, particularly in the case of roads and railwaysclose to residential areas, a known solution is provide sound barrierwalls between the noise source and an area desired to have lowered noiselevels. Sound barrier walls operate primarily on the principle of noisereflection, wherein a portion of the noise energy from a noise source isreflected back toward the source or at least away from the desired noisereduced area. A problem with such walls, however, is that noise or soundenergy has both a magnitude or amplitude (e.g., sound pressure indecibels), as well as a direction. Thus, a certain amount of noiseeither projects directly over the barrier, some noise is diffracted atthe top of the barrier back down toward the area on the other side ofthe barrier, and still further, some of the noise is transmitted throughthe barrier wall itself.

These problems are illustrated by FIG. 1, wherein some of the noise fromnoise source 102, such as a vehicle on a roadway, is reflected away bybarrier 103 from an area 104 where noise reduction is desired as shownby vector 105. However, particular noise from source 102 having adirection of travel upward will pass over barrier 103 as indicated byvectors 108. Additionally, portions of this noise are diffracted fromthe top of barrier 103 downward to the area 104, thus increasing ambientnoise levels. This noise can approach 70 dBA or greater. Finally, sincethe noise barrier 103 is sound reflecting with poor sound absorptionproperties, a portion of the noise from noise source 102 will betransmitted through the barrier 103 as illustrated by vector 112.

There is therefore a need in the art for better mechanism for soundabsorption, and, in particular, for a sound absorption mechanism that iscapable of being placed by roadways and other similar noise sources forimproved noise reduction.

SUMMARY

According to a first aspect, a sound absorbing panel is disclosed havingan enclosure including a first panel face including a plurality ofapertures or holes that allow for the passage of sound energy. The ratioof the area of the apertures to the total area of the first panel faceis set at a predetermined percentage, with the first panel face having afirst side comprising an outer surface of the enclosure and a secondside comprising an inner surface of the enclosure. The panel furtherincludes a fibrous sound absorbing material having a first side with anarea approximately equal to the total area of the first panel face andthe first side of the sound absorbing material disposed proximate to thesecond side of the first panel face.

In another aspect, a sound absorbing panel system is disclosed thatincludes one or more sound absorbing panels configured to be mounted toa surface positioned to receive incident noise from one or more noisesources. Each of the one of more sound absorbing panels has an enclosureincluding a first panel face including a plurality of apertures or holesthat allow for the passage of sound energy. The ratio of the area of theapertures to the total area of the first panel face is set at apredetermined percentage, with the first panel face having a first sidecomprising an outer surface of the enclosure and a second sidecomprising an inner surface of the enclosure. The panel further includesa fibrous sound absorbing material having a first side with an areaapproximately equal to the total area of the first panel face and thefirst side of the sound absorbing material disposed proximate to thesecond side of the first panel face.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of how noise travels in a system usingreflective noise barriers;

FIG. 2 is an exploded trimetric view of an exemplary sound absorbingpanel;

FIG. 3 is a side sectional view of the assembled sound absorbing panelof FIG. 2;

FIG. 4 is an trimetric view of another exemplary sound absorbing panelhaving an angled portion;

FIG. 5 is an trimetric view of yet another exemplary sound absorbingpanel having an curved portion;

FIG. 6 is a trimetric view of a sound barrier wall including a soundabsorption system comprising a plurality of the presently disclosedsound absorbing panels mounted on the barrier wall.

DETAILED DESCRIPTION

The present invention provides a sound absorbing panel and system thatprovides exceptional sound absorbing/noise reduction performance thatpreviously has not been achieved with sound absorbing panels, such aspanels for reducing road noise. In particular, the presently disclosedpanels combine a fibrous textile material with sound absorbingproperties with a particular face having a specific aperture to area ofsound absorbing ratio. This arrangement may be put together in a housingthat allows for positioning and easy attachment of the sound absorbingapparatus to existing wall structures, such as sound barrier walls 103.Furthermore, the panels may be configured with different face topologiesto better meet directional noise and mitigate diffraction over soundbathers.

FIG. 2 is an exploded trimetric view of an exemplary sound absorbingpanel according to the present disclosure. The panel 200 may beconfigured as an enclosure including a first portion or panel face 202including a plurality of apertures 204 that allow sound energy to passto sound absorbing material 206. Additionally, the enclosure may includea second portion or backing portion 208 for enclosing the material 206when assembled and meeting with the first panel face 202.

Sound absorbing material 206 is composed of a textile fibrous soundabsorbing material. As one example, the material 206 may have acomposition including thick cotton textile material, such as denim In aparticular aspect, the material 206 may comprise bonded, highperformance recycled cotton fiber material manufactured by Bonded Logic,Inc. of Chandler, Ariz.

In an embodiment, the material 206 may be monolithic and rectangular inshape as illustrated in FIG. 2, but is not limited to a single piece ofmaterial or a rectangular shape, and could be configured in any numberof various shapes (with the enclosure 208 and face 202 matching theshape of the material). In another aspect, the thickness 210 of material206 is 2 inches or greater to provide optimal sound absorption, but thethickness may be less if desired or if size constraints exist.Additionally, the construction of material 206 is configured to afford adegree of rigidity and tensile strength such the material 206 may bemanipulated to accommodate different topologies of the panel face 202(as will be discussed later), while still maintaining shape and rigidity(i.e., termed herein as “semi-rigid”) such that if the larger planarsurface of panel 200 is placed vertically (i.e., the plane of firstpanel face 202 is vertical), for example, material 210 will not sag butremain durable and in place substantially occupying the volume of theenclosure (i.e., the enclosure defined by the combination of face 202and portion 208).

FIG. 3 shows a side sectional view of the assembled sound absorbingpanel of FIG. 2. As may be seen in this embodiment, material 206 fillsthe back of the enclosure 208 and has a surface 214 with area equal orat least approximately equal to the area of the first panel face 202.This surface 214 is disposed proximate to or abutting an inner face 216of the panel face 202. All of the apertures 204 in panel face are thusoccluded by the material 202 on the inside face 216 to ensure that soundpassing through each aperture impinges on the material 206.

It further noted that having surface 214 may have an area approximatelyequal to the total area of the first panel face (i.e., 212), and theratio of the area of the apertures 204 to the total area of the firstpanel face 212 is set at a predetermined percentage or ratio. In anaspect, a ratio of approximately 0.23 (or 23%) has been found to providean optimal ratio for providing maximum sound absorption. It is noted,however, that this ratio is not intended to be limiting, and that otherratios could be used in the presently disclosed panels. Additionally,although the apertures 204 are illustrated as round or circular,apertures 204 could be configured in other shapes such as ovals orvarious polygonal shapes, as merely two examples. Furthermore, thepattern of the plurality of apertures 204 may be arranged such that thecenters of the apertures are spaced equidistant or at regular intervals,but is not necessarily limited to regular patterns.

The materials used for constructing the first panel face 202 and theenclosure portion 208 may be any suitable material(s) known in the art.For example, face 202 and portion 208 may be constructed of one or morea plastic, such as polymers (e.g., polyethylene) or copolymers (e.g.,ABS), metals such as aluminum or steel, composites, fiberglass, wood,etc.

Although panel 200 is illustrated herein in a rectangular configuration,one skilled in the art will appreciate that the shape of the panel isnot so limited and could be configured in various polygonal shapes,conic sectional shapes, or in random or stylized shapes. Furthermore,the example of FIGS. 2 and 3 illustrate a substantially planar panel,but it is noted that angled or curved configurations are contemplated aswill be discussed below.

FIG. 4 is an trimetric view of another exemplary sound absorbing panel400 having an angled portion and employing the principles, materials,and aperture configuration of the panel in the example of FIGS. 2 and 3.As illustrated, panel 400 may include a first portion 402 lyingsubstantially in a plane illustrated by line 403. A second portion 404is angled at angle a 406 with respect to plane 403 and, therefore,portion 402. It is contemplated that with this angled construction, ifthe panel were located at the top of noise barrier wall (e.g., 103 inFIG. 1), the angle portion 404 may be better oriented to meet incidentnoise (e.g., noise 108 shown in FIG. 1) at incident angles that provideoptimal performance for a particular application of the panel.

Panel 400 includes the sound absorbing material 206, which having asemi-rigid property may be angled within the panel 400. In an alternateembodiment, two or more separate pieces of the material 206 may be used,such as one piece for portion 402 and another piece for portion 404. Instill another alternative, it is contemplated that the junction ofportion 402 and 404 may be joined in a hinged manner (not shown)allowing the angle a to be varied and set to an angle that achievesoptimal sound absorption for a particular installation.

FIG. 5 is trimetric view of yet another exemplary sound absorbing panel500 having an curved construction and employing the principles,materials, and aperture configuration of the panel in the example ofFIGS. 2 and 3. Similar to angled panel 400, panel 500 may include aplanar portion 502 and another portion 504 that is configured in acurved manner. The particular radius of the curve may set to any of anumber of values, and also need not be a constant radius, but couldeither an accelerating or decelerating radius as desired. The curvedconfiguration is contemplated to allow sound absorption over a widerangle, and affords a variable surface (i.e., the curve has a changingperpendicular point (i.e., a gradient) by its nature) that can moreeffectively absorb variously angled sound waves impinging thereupon. Inan alternative, it is contemplated that panel 500 could be constructedwithout planar portion 502, and simply be an entire It is noted thatboth panels 400 and 500 may be particularly useful when mounted high ona wall structure, such as barrier 103, although it is also contemplatedthat they may be useful mounted lower on a wall as well.

FIG. 6 is a trimetric view of a sound absorption system including thepresently disclosed sound absorption panels with a sound barrier wall(or other structure). In the exemplary system 600 of FIG. 6, a structure602, such as a highway or railway sound barrier wall, may incorporate asystem of one or more various sound absorbing panels 604, 606, 608. Thesystem 600 incorporates one or more of the presently disclosed soundabsorbing panels being configured to be mountable to structure 602 (orany vertical, angled, or horizontal surface to which unwanted noise isincident). As illustrated in this example, flat panels 604, curvedpanels 606, or angled panels 608 (or any combination thereof) may beemployed. In an aspect, the curved or angled panels 606, 608 may bebeneficial when placed near the top of structure 602 as shown to betterabsorb noise that would otherwise pass over a barrier and be diffracteddownward. In addition to shape, the number or density of the panels canbe tailored to a location, such as to minimize the cost but meetingrequired sound absorbent levels, or alternatively the panels may beinstalled as a dense array of a plurality of panels with small or nogaps therebetween. The panels can be used in new installations orretrofitted to existing structures. With respect to retrofitting, inparticular, it is noted that there are over 2000 miles of existing soundreflective barriers used on highways in the United States. Thus, thepresent system is particularly beneficial in providing a means to addactual sound absorption as a retrofit to existing structures, thussaving cost by not having to erect new structures for thousands of milesof highway to implement the system.

Although the presently disclosed sound absorbing panels have beendescribed in the context of highway and railway noise absorption, thepresent panels could be used in any environment where unwanted noiseimpinges on a space such as around construction sites, airports, or eveninside buildings.

Of final note, an embodiment of the disclosed sound absorbing panel wastested at the Riverbank Acoustical Laboratories (RAL)™ usingReverberation Room Method ASTM C 423-07NVLAP 08/P03. The tested panelhaving approximately 23% of the face of the panel comprising aperturesreceived a test result of 0.95 Noise Reduction Coefficient (NRC). Thiscoefficient effectively means that 95% of the sound impinging on thepanel was be absorbed, which is a result not known to Applicant to havebeen achieved by such type of sound absorbing panels previously. Thus,the novel combination of the fibrous textile material and a panel facehaving a specific ratio of aperture area to total surface area has beenshown to provide exceptional sound absorbing properties.

The present description of the disclosed examples is provided to enableany person skilled in the art to make or use the present invention.Various modifications to these examples will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other embodiments without departing from the spirit orscope of the invention. Thus, the present invention is not intended tobe limited to the embodiments shown herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

1. A sound absorbing panel comprising: an enclosure including a firstpanel face including a plurality of apertures, wherein the ratio of thearea of the apertures to the total area of the first panel face is setat a predetermined percentage, the first panel face having a first sidecomprising an outer surface of the enclosure and a second sidecomprising an inner surface of the enclosure; a fibrous sound absorbingmaterial having a first side with an area approximately equal to thetotal area of the first panel face and the first side of the soundabsorbing material disposed proximate to the second side of the firstpanel face.
 2. The panel as defined in claim 1, wherein thepredetermined percentage is 23%.
 3. The panel as defined in claim 1,wherein each of the plurality of apertures are round.
 4. The panel asdefined in claim 1, wherein the first face is planar.
 5. The panel asdefined in claim 1, wherein a first portion of the first face lies in aplane and a second portion of the first face is angled away from theplane.
 6. The panel as defined in claim 1, wherein a first portion liesin a plane and a second portions curves and extends away from the plane.7. The panel as defined in claim 1, wherein the fibrous sound absorbingmaterial comprises at least cotton denim fibers.
 8. The panel as definedin claim 1, wherein the fibrous sound absorbing material is semi-rigidand monolithic.
 9. The panel as defined in claim material has thicknessof at least approximately 2 inches.
 11. A sound absorbing panel systemcomprising: one or more sound absorbing panels configured to be mountedto a surface positioned to receive incident noise from one or more noisesources, each of the one of more sound absorbing panels comprising: anenclosure including a first panel face including a plurality ofapertures, wherein the ratio of the area of the apertures to the totalarea of the first panel face is set at a predetermined percentage, thefirst panel face having a first side comprising an outer surface of theenclosure and a second side comprising an inner surface of theenclosure; and a fibrous sound absorbing material having a first sidewith an area approximately equal to the total area of the first panelface and the first side of the sound absorbing material disposedproximate to the second side of the first panel face.
 12. The system asdefined in claim 11, wherein the predetermined percentage is 23%. 13.The system as defined in claim 11, wherein a first portion of the firstface lies in a plane and a second portion of the first face is angledaway from the plane.
 14. The system as defined in claim 11, wherein afirst portion lies in a plane and a second portions curves and extendsaway from the plane.
 15. The system as defined in claim 11, wherein thefibrous sound absorbing material comprises at least cotton denim fibers.16. The system as defined in claim 11, wherein the fibrous soundabsorbing material is semi-rigid and monolithic.
 17. The system asdefined in claim 11 wherein the fibrous sound absorbing material hasthickness of at least approximately 2 inches.
 18. The system as definedin claim 11, wherein the surface comprises at least one of a highwaysound reflecting barrier wall and a railroad sound reflecting barrierwall.
 19. The system as defined in claim 18, wherein the surface is partof existing structures and the system is further configured to bemountable to the surface as a retrofit system.